Process for the continuous production of low-boiling-point hydrocarbons from petroleum oils



R. W. HANNA. PROCESS FOR THE CONTINUOUS PRODUCTION OF LOW BOILING POINT HYDROCARBONS FROM PETROLEUM OILS.

APPLICATION FILED JAN. 19, 1920.

1,419,378,, Patented June 13, 1922.

2 SHEETS-SHEET I.

H. WQHANNA'. PROCESS FOR THE CONTINUOUS PRODUCTION OF LOW BOILING POINT HYDROCARBONS FROM PETROLEUM OILS.

APPLICATION FILED JAN. 19, 1920.

1,419,378, PatenteN June 13, 11922.

2 SHEETSFSHEET 2.

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RICHARD W. HANNA, or moHMoNn, GALIFORNIA, ASSIGNOR TO STANDARD OIL COMPANY or CALIFORNIA, or SAN rnANcrsco, cALI'roRNIA, A oonrona'rrom or CALIFORNIA.

PROCESS FOR THE CONTINUOUS PRODUCTION or LoW-BoILrNG-PoIN'r HYioRooARBoNs To all whom it may concern."

Be it known that I, RICHARD W. HANNA,

a citizen of the United States, residing at Richmond, in the county ofContra Costa.

and State of California, have invented a new and useful Process for the Continuous Production of Low-Boiling-Point Hydro.-

jcarbonsfrom Petroleum Oils,of which the following is a specification. i

Thisinvention relates to the art of producing low boiling point hydrocarbons, such for example as motor spirits, from high-er boiling point petroleum oils, crude oilsand residuums. I

I have discovered that the distillate produced by the generally accepted processes of destructive or ordinarydistillation forms carbon and carbonaceous matter'when further destructive distillation thereof is attempted. This is due to the reduced hydrogen content of the distillate produced by such destructive or ordinary distillation.

This can be overcome by preserving. thehydrogehcontent by distillation under a reduced pressure les than atmospheric preventing decompositionor the formation of unsaturated hydrocarbons. V

The distillation of a petroleum oil under a reduced'pressure sufiicient to lower the vaporizing temperature below. said petroleum oil'decomposingior cracking temperature conserves the hydrogen content ofthe oil so that the formation of'unsaturated hyclasses of unsaturated and aromatic hydrocarbons t'end to polymerize, resulting in the formation of very heavy, tarry residues,

which very readily formicarbon, and others upon being cracked-tend to decompose direct into carbonaceous matter. By'preventing the formatio of more wrrsaturated, bodies; or aromatics 'tha' contained in the original stock, I am able to crack the resultant dis I tillate with aminimum production ofheavy tarry residueandcarbonaceous matter. In

natural crude petroleum oils there are vary ing percentages of unsaturat'ed hydrocarbons which in'some cases-may be as high as I do not confine myself to any fixed percentage of hydrogen By my method,

FROM PETROLEUM OILS.-

: till'ate-to carbon 'oil.

duced, pressure, less than atmospheric pressure, there is substantially no further productionof unsaturated hydrocarbons. of such class that tends to form such undesirable tarry bodies or carbonaceous-matter when the resultant distillate is subjected to a cracking process. i

I I Patented June 13,1922.

Application filed January 19, 1920. Serial No. 352,416.

An object of the invention isto produce T first, a relatively uniform high boiling point hydrocarbon distillate or fraction, either from a crude oil, a residuum or'from a previous distillate; which shall contain. the highest possible hydrogen content, inflorder that the same may be cracked to produce low boiling point hydrocarbons, or motor spirits, therefrom most advantageously, and, second,

u content derivable fromthe stock employed and which distillate'may be introduced into the second step of the process and cracked to produce low boiling point hydrocarbons with the minimum production of carbonaceous matter or tarry' bodies,"thereby'substantially eliminating theusual disadvantages and trjoubles attendant from the product-ionof carbonaceous matter and tarry bodies in a cracking apparatus or process.

"In the preferred form of my invention 1* first produce by distillation under a pressure less than atmospheric arlatively uniform high. boiling point hydrocarbon distillate and then subject such distillate to destruc-- tive distillation. a

Broadly,.myinvention consists in maintaining, first, a dlstilli'ng o eration at a sub stantially constant reduce pressure,so that the vaporizing temperature of the oil under distillation. is below its decomposing or cracking temperature, and thus maintain a, maximum hydrogen content in the vaporized distillate, and thereafter cracking this disproduce a low boiling point ,hydro-.

, In its detailed or m pecie aim the.

to provide as a part of such'process for the first distilling operation is preferably carried on continuously, and the cracking operation is preferably performedias a continuous cracking operation, or step.

More specifically, the preferred embodiment of my invention 'consists in maintaining, first, adistilling operation at a substantially constant reduced pressure, so that the vaporizing temperature of the oil under distillation is below its decomposing or cracking temperature, and thus maintaining the maximum hydrogen content in the vaporized distillate, preferably con tinuously introducing the oil to be distilled, preferably continuously withdrawing the vapors of such distillation, and preferably continuously withdrawing the residual oils, and second, inperforming the cracking operation by continuously introducing the high boiling point distillate so produced by thev vapors of the first distillation, into a cracking system or'apparatus, maintaining in such cracking apparatus or system during the cracking operation a substantially constant volume of such distillateunder a pressure reater. than atmospheric and at a substantia ly constant pressure and temperature sufficient to crack such distillate, continuously withdrawing the low boiling point fraction produced as vapor.

and substantially continuously withdrawing the residual oil.

.tothe over-heated condition of the metal. --Also with such depositions the apparatus cannot be operated continuously but must i. be shut down at intervals to clean out the accumulations. This results in loss of time, efliciency and capacity.

The invention will be more read ly understood by reference to the accompanying.

drawings in which an apparatus is indicated by means of which the preferred embodiment of my process maybe carried out.

In these drawings:

Fig. 1 is a plan view of so much of the apparatus as is utilized in the first distillation under reduced pressure, and

Fig. 2 is a side elevation thereof.

Fig. 3 is a diagrammatic illustration of the apparatus. wherein the second distillation or cracking isperformed.

Figs. 1 and 2 illustrate an apparatus-for the continuous distillation of. a high boiling point fraction and by means thereof the exchanger 7, thence similarly through-the heat exchanger 9 in pipe 10 and then into the tar heat exchanger 11. From the latter the oil passes into the pipe 12 and is discharged continuously into the still-14.

The passage of the oil 'as described from storage pipe 1 to a still 14 is continuous and is preheated by the outgoing oil vapors from stills 14, 35 and 56 by means of the heat exchangers 5, 7 and 9 which are arranged in a series so that the greatest heat exchange possible is effected. From heat exchanger 9 the oil to be distilled passes through heatexchanger 11 wherein said oil is further heated by an exchange of heat from the outgoing hot residual oil. While this is the preferred order andarrangement, this order of preheating the incoming oil to be diistilled maybe varied or changed as desire From the still 14 the oil passes through pipe 33' into still 35 and in like manner -the oil from still 35 passes through the pipe 54 into the still 56.; These stills are heated in any"'usual-orpreferred manner. The

temperature of theoil as' maintained in be carried out either with or without theintroduction' of steam. 83 indicates a pipe in an equalizing line common to the stills 14, 35 and 56 whereby the pressure maintained in said stills is'the same at all times; 4

7 6 indicates a pipe to conduct the hot residual oil to the tar heat exchanger 11 connected to the suction side of the pump '77.

Pump 77 dischargesinto a line which leads 1 into a tar cooler 78 connected by a pipe. 79 to storage tank 80. The flow of oil through the system is regulated by means ofthe pump 77. c 15, 36 and 57 represent vapor lines which conduct the products of distillation to vapor heat exchangers 5, 7 and 9 where a fraction of. the vaporized oil or oil and steam is condensed and conducted through condensers 94, 92, 93, and thence by pipes 25, 46 and 67 through pipes 91, 90 and 74.

able connections which leadtothe receiving The necessary reduction of pressure or vacuum is maintained on the system by vacuum pump 82 which is connected to receivers 19, 28, 40,49, 61 and 71 by means ofia pipe 95and manifold pipe 81..

Preferably duplicate storage tanks are provided foreach still. Therefore in the drawings I have indicated storage tanks 23, 44, and 65 to which the distillate from the respective stills 14, 35, 56 may be conducted and have shown duplicate pumps 21,42, 43, by which the distillate from said respective stillsis pumped to such storage tanks. 17, 38, 59, indicate the look boxes and 19, 40, 61 the receivers or'vacuum pots in the line or system to such storage tanks 23, 44, 65, re-* spectively.

In this apparatus as thus indicated for performing the first distillation I have indicated a battery of three stills, but my invention is not limited to the use of any particu-' lar number of such stills, since a greater or less number may be used in accordance with the production desired.

It is obvious that-suitable valvesmay be provided in connection with the pipe 83 so that each of the stills may be operated without equalization with reference to the other or .any coupling of thestills together for such equalizing purposes may be provided.

In Fig. 3 tanks 101 and112 represent suitable storage vessels for the distillate or oil to be cracked. These are provided with suittanks 23, 44, 65, 75, 53 and 32 connected by manifold pipe 100. (See Fig. 1). 1'

In Fig. 3 is illustrated the preferred form of apparatus for the second distillation or cracking operation. In such Fig. 3, 102 and 113 represent pumps for handling the disvtillateto-be cracked and discharged into pipe 103 through a valve 114 into an evaporator 105. 106 represents a circulating pump connected on its suction side with a pipe107 to the evaporator 105 and on its discharge side with a pipe 108 leading to the heating ele-' ment, preferably a coil 109 in a furnace 110, being connected by a suitable pipe 111 to the evaporator 105. J v

116 is the vapor line from the evaporator 105; 117 represents a dephlemator in said lin 116. 118 indicates a condenser connected with said dephlemator; 119 represents a suit-able receiver connected with the con denser and 120 a'valve whereby the pressure may be released or regulated and the condensate' delivered for storage.

121 represents a discharge pipe from the evaporator 105; 122 a cooler to which the pipe 121 leads. the cooler and 124 a reservoir.

125 represents a receiving pan in the evap- 123 a discharge valve from orator 5 connected to a pipe 126. 127 is a T with an open end openinginto the connec tion of the pipe 107 through the end of the evaporator 105.

.The apparatus thus illustrated ig; 3 is a preferred form of apparatus which I prefer to use in the cracking step of my process.

oil of relatively low boiling points containing an unusually high percentage of naphthene and aromatic hydrocarbons or it may be any low boiling point fraction of the same, or any other oil which will'be substantially unaffectedat the pressure and .temperature employed in the cracking step of the process. The function of the solvent oil as thus .used in the cracking step of my process is to keep the heavy bodies resultant from the "cracking in dilute condition or in solution so that the resultant heavy bodies may be dischargedfrom the system in solution or in dilute condition, thus substantially preventing the deposition of carbon in the apparatus or system.

From the evaporator 105 the solidhydrocarbons, heavy bodies or tarry residues in My improvementin this step of the process, which improvement I preferably utilize when it is desired to secure all of the solution orin dilute condition in the solvent oil are discharged in the valve 121 and cooler 122 into the receiver 124 at such a rate as to keep the saturation of the solvent oil with the heavy bodies, heavy hydrocarbons or tarry residues therein below such a degree of concentration that upon further circulation and heating such solvent oil may --take into solution the further high boiling, point fractions produced from the crackalole oil without permitting such heavy hydrooarbons to become too concentrated in the ap paratus. If the solvent oil is permitted to become overcharged with such heavy hydroy carbons deposition takes place as these heavy hydrocarbons take the brunt of the heat and unless held in solution or in dilute condition by the solvent oil becomes further reduced to carbon. The degree of concentration of the solvent oil and h boiling point fraction produced by the cracking'of the crackable oil,) which may be permitted in the operation of my process Without danger of deposition will, of course, depend upon the oils charged into thesystem, as for example, the carbon residue test should 'not exceed ten times that in the charged oils. This .is merely an example and will vary with the oils. In the cracking of certain petroleum distillates there may be produced from the cracking operation itself, suflicient solvent or non-crackable oil of un saturated form to keep the solid hydrocar-' bons, heavy bodies or tarry residues in solu-' tion or in dilute condition so that no deposition will form on the metal surfaces of the heating element, in which case it is unneces sary to add a separate solvent or non-crackableoil from an outside source. I therefore do not limit myself to the use of a solvent or non-crackable oil to be introduced from an outside source, .since suflicient may be produced in the operation when certain I petroleum oils are used.

A certain amount of non-crackable or solvent oil passes ofi with the solid hydrocarbons, heavy bodies or tarry residues in. solution or in dilute condition. This may be replaced from storage as required.

As an example of the. proportion of the oil to be cracked as to the proportion of solvent oil, I add one volume of the former to as much as three or five volumes of the latter in the system at any given time. This may be varied in accordance with the oils treated. As an example of a desirable cracking pressure and temperature for the oil to be cracked-I give 105 to'120 pounds absolute and 745 Isl-800" F., but it is understoocl that these proportions and the pressure and temperature may vary according to the oils used.

In practice the solvent oil and the oil to be cracked may be mixed and thus introduced not only in charging the apparatusfor starting the cracking distillation but also in the continued operation thereof.

It is also obvious that any relatively low boiling point oil may be used as the solvent oil provided it is substantially unaffected at the pressure and temperature of the operation. f

. By constantly feeding into the a paratus or system such a quantlty of the so vent oil and oil to be rackedas will maintain a substantially nstant volume in the apparatus and maintain continuous crackin at substantially the determined pressure and temperature, a substantially uniform frac- 60\ tion is continuously produced. during the cracking "operation.

While llhave thus referred and do here after refer in the claims to the solvent oil and the oil to be cracked as two oils it will 65 be understood that I do not limit my invention to the use of two distinct oils inv clude as within my process and invention and Within the cracking step thereof the cracking of any oil which contains fractions, I

one of which Will be cracked at a given pressure and temperature and another frac- ,tion which will .be substantially unaffected by pressure and temperature and which will act as a solvent oil as heretofore'fexplained. It is thus obvious that lam not necessarily limited in my process to the use of a solvent oil produced by the first step of my process;

It is also to be understood that my method,

y is not confined to the use of any particular solvent oil, the distillate from refractory California cru e mentioned bein given merely as an example of a solvent Oll which is relatively unaffected by the pressure and temperature to crack the oil to-be treated. In the appended claims I refer to a rela tively high boiling point fraction or distillate produced from a petroleum oil by distillation at a reducedpressure less than atmospheric, whereby in :such distillate the maximum hydrogen content of such petroleum oil' is conserved, as a distillatecomposed of substantially saturated hydrocar bons to distinguish the same from a distillate in which either unsaturated hydrocarbons oraromatics formed bydistillati'on are present, which tend either to such polymerization or to decomposition into carbonaceous matter, as before explained.

I claim 1. The 'art of cracking petroleum oil to produce a low boiling point distillate from a relatively higher boiling point fraction, which includes distilling an oil under a reduced pressure less than atmospheric whereby decomposition is substantiall' prevented, and then subjecting a relatively i-gh boiling point fraction thus produced to a temperature and pressure sufficient to crack the-same to produce a low boiling point distillate.

2. In the art of producing a low boiling point distillate u from. a relatively higher boilin point fraction of -ahydrocarbon oil, distilling the oil under a reduced pressure sufficient to lower the vaporizing temperature below the decompqsingtemperature of such oil, thereby producing a relatively high boilingpoint fraction thereof with the hyvdrogen content of; the original oil substanproducing a relatively high boilin point 0 fraction and whereby the formation of unsaturated hydrocarbons in said. fraction is corresponding substantially to the hydrogen content of the corresponding fraction of the original oil, in conjunction with a solvent oil; maintaining in said system a pressure and temperature required to crack said distillate; continuously passing out of the system the low boiling point vapors from said cracked oil, and continuously removing from said system the resultant solvent oil solution 5. In the method of cracking a relatively high boiling point hydrocarbon to produce a relatively low boiling point distillate, the step which consists in continuously circulating conjointly a relatively high boiling point distillate, composed of hydrocarbons having a hydrogen content corresponding substantially to the hydrogen content of the corresponding fraction of the original oil in conjunction with a solvent oil under conditions of pressure and temperature adapted to crack only said distillate, whereby the relatively higher boiling point fractionsof suchdistillate are carrled in dilutei condition by said solvent oil.

6. The process of cracking a relatively high boiling point hydrocarbon to produce a substantially uniform relatively low boiling point distillate, which consists in continuously feeding into and rapidly moving through a closed system a relatively high boiling point distillate, composed of hydrocarbons, having a hydrogen content corre sponding substantially to the hydrogen content of the corresponding fraction of the original oil, and a solvent oil, maintaining 1n said system a substantially constant volume, pressure and temperature, said temperature and pressure being, that adapted to crack said high boiling point distillate,

whereby the relatively higher boiling pointfractions from said distillate are carried in dilute condition said solvent oil, continub ously passing off om the system the vapors of distillation, and maintaining the resultant solutlon by dllution and suitable discharge from becoming sufiiciently concentrated to composed of hydrocarbons, having a, hydrov gen content corresponding substantially to the hydrogen content of the corresponding? fraction of the original oil, and a solvent oil,

maintaining in the system a cracking pressure and temperature required for the first named distillate but inefi'ective to crack the solvent oil, the heat being applied to one portion of the system, whereby through said pressure and temperature the first named distillate only is cracked and the relatively higher boiling point hydrocarbons produced by such cracking are carried in dilute condition by the solvent oil, continuously passing'off from the system at points removed from said portion to which the heat is applied the low boiling point vapors of distillation, and the resultant residual solution.

8. The process of producin low boiling point distillate from hydrocar on oil which consists in distilling an oil under a reduced pressure sufficient to lower the vaporizing temperature below the decomposition temperature of such oil, continuously circulating conj ointly a relatively high boiling point distillate thereby produced conjointly with a solvent oil under conditions of pressure and temperature adapted to crack only said distillate, whereby the relatively higher boiling point fractions from such distillate are carried in dilute condition by said solvent oil, withdrawing the resultant low boiling 

